Prospectors discovered gold in Alder Gulch, Idaho Territory, on May 26, 1863. Within weeks, the countryside was teeming with thousands of prospectors, but the easily extracted placer gold soon played out. B. F. Christenot, acting independently or perhaps as agent to Philadelphia backers, began acquiring claims in the Summit Mining District in 1864. Christenot later concealed a substantial amount of gold on his person and traveled to Philadelphia where he convinced investors to back construction of a mill. The transition from placer to lode mining, an expensive undertaking that required heavy financial backing, is well documented here at Union City. Machinery, transported in twenty-six ox-drawn wagons over the Bozeman Trail, arrived in October 1866. Thompson and Griffith of Virginia City constructed the mill, which operated by spring 1867. In June, journalist A. K. McClure arrived from the east to assume its management. Most milling of this period was accomplished by stamping, but the Union City operation employed a process using Chilean rollers for crushing the quartz. Although the mill was reported to be the most efficient in the territory, the ore was soon exhausted and the mill closed down in spring 1868. Sixty thousand dollars was said to have been extracted from the company’s nearby Oro Cache lode, but the equipment alone cost $80,000; the operation was a financial disaster. At peak production the Christenot Mill employed up to forty workers, and the site, representing all aspects of gold milling technology from processing to management, fills a significant chapter in the history of mining in Montana.